Charting: TimeSpan on Dependant Axis

I'm collecting process runtime statistics, and want to show the time the process took to run for every run. I'm currently doing this with a different wpf charting component but I would love to use the wpf toolkit charting component instead.

Am I right to say it's currently not possible? Would it be considered as a feature anytime soon?

What I do now is add the TimeSpan to a DateTime (2000-01-01 00:00:00.000) and format the output to only display hours, minutes and seconds. Full TimeSpan support would be great, because a DateTime with 0 for date does not work and neither for month and year.